PDATE comments
SET `comment` = (
CASE
        WHEN id % 2 = 0 THEN 'Very good article.'
        WHEN id % 3 = 0 THEN 'This is interesting.'
        WHEN id % 5 = 0 THEN 'I definitely will read the article again.'
        WHEN id % 7 = 0 THEN 'The universe is such an amazing thing.'
        ELSE  `comment`
end
) WHERE id BETWEEN 1 AND 15;